1. Field of the Invention
This invention relates to color imaging by photochemical oxidation of leuco dyes.
2. Description of the Prior Art
Photochemical oxidation of leuco dyes is well known in the art. It is also known to employ sensitizers in the system to increase the rate of leuco dye oxidation, and a variety of sensitizers have been employed for this purpose. In U.S. Pat. No. 3,121,632 Sprague et al. describe the use of aldehydes and/or ketones as activators. In U.S. Pat. No. 3,390,996 MacLachlan teaches photosensitive compositions containing a leuco dye such as an aminotriarylmethane, a photooxidant such as a hexaarylbiimidazole, and a redox couple which is a combination of a reductant and an oxidant. In a long list of suitable reductant components, several aromatic aldehydes are mentioned. Suitable oxidants include aromatic ketones and quinones.